This invention relates to a quick release grouting valve system for injecting grout into an inlet port for grouting skirt piles within skirt sleeves at the bottom of a platform so as to anchor the platform to the ocean floor at a deepwater location.
Offshore structures in the form of large offshore platforms are erected on the ocean floor for the purpose of drilling a large number of wells into the ocean floor in order to develop oil and/or gas fields. Typically, a platform takes the form of a rectangular structure with a plurality of legs upwardly extending from the ocean floor to a point above the surface of the water where a platform deck is supported by the legs. In order to anchor the structure to the ocean floor and prevent its overturning, the structure is usually provided with a plurality of short skirt sleeves in the form of elongated cylindrical elements welded to the lower end of the platform and extending substantially parallel to the legs thereof. A smaller diameter tubular pile is driven through the skirt sleeves to a secure reception in the ocean floor, the top of the pile is cut off, and the pile and skirt sleeve are then cemented together.
A common method of cementing piles within skirt sleeves in accordance with prior art uses a cementing pipe welded to each of the legs of the platform. Each cementing pipe extends from the top to the lower end of the platform where a lateral pipe runs to one or more skirt sleeves which are outboard of the legs of the platform. After a pile has been driven and cut off to desired length, grout is pumped down the cement or grout line outside of the leg, and through the crossover lateral pipe which is in communication of the interior of the skirt sleeve, and fills an annular space between the pile and the skirt sleeve.
The Applicant has improved the grouting system described above and is proposing the use of a system using a flexible grouting hose deployed from a service barge. This improved system is the subject of a co-pending application filed by the present Applicant for a platform grouting valve system and method. In the improved method a supply of grout, a grout pump, and one or more underwater remotely operated vehicles (ROVs), together with lowering winches and control stations for the ROV are provided by the service barge. Further, each of the skirt sleeves is provided with one or more valved grout inlet ports. A connection is established in the lower end of the grouting hose and the grout inlet ports of the skirt sleeves and a slurry of grout is pumped down through the grouting hose and into the annular space formed between the pile and the surrounding skirt sleeve.
The ROV then disconnects the grouting hose from the grout inlet port and flies through the water towing the flexible grouting hose behind it so as to stab the next grout inlet port and so on through successive grout inlet ports and pile sleeves of the structure. If desired, a series of grout inlet ports may be arranged vertically at spaced apart intervals along the pile sleeve which may be several hundred feet or more in height so that individual sections of the annular space may be separately grouted. Preferably, the grouting hoses are connected first to the lowermost inlet port on the sleeve so that the grout flows upwardly to the annular space within the sleeve and out the top thereof.
Thus, it can be seen that the practice of such a grouting system requires a large number of connections to be established, moved and reestablished between grout inlet ports and the lower end of the grouting hose. However, connections such as between the grouting hose and the grout inlet ports are difficult to establish in deep water applications. This is particularly true at depths for which the use of divers is generally not feasible and ROV operations must be relied upon. Therefore, there is a need for a platform grouting valve system which is particularly adapted for ROV operation. Further, a platform grouting valve system suitable for such connections must also provide for efficient disconnection to facilitate repeated placement, connection, grouting operations, and redeployment as each of the piles are grouted about the base of the platform.